Being a very stable genius means never having to say you're sorry. Especially when you've been busy putting on a show.

After President Donald Trump acted out in his meeting with our allies in the North Atlantic Treaty Organization on Thursday, he then shifted gears and made nice, pretending that all was just swell. And that all parties were fine friends.

Shortly after the contentious NATO meeting, though, Trump took a moment -- again -- to declare himself a "very stable genius." Really.

Herewith, a rule of thumb worth remembering: Very stable geniuses don't spend much time asserting that they are very stable geniuses.

Trump's Friday schedule included a meeting with May and afternoon tea with Queen Elizabeth II. On the eve of those get-togethers, though, an interview published by the British tabloid The Sun, appearing at 11 p.m., cast a pall over the Friday events.

Here was Trump on May's plans for a so-called soft Brexit, a compromise way to get Britain out of the European Union:

"I would have done it much differently," Trump said. "I actually told Theresa May how to do it, but she didn't listen to me."

As per usual, Trump believes he alone knows best.

The Daily Mirror, another British tabloid, hit newsstands on Friday with the following headline on the cover: "The ego has landed."

NATO, which is now 29 nations strong, survived Trump's bad behavior. For now. Though he has threatened to go his own way if member nations don't agree to his demands to up their antes to the alliance. One can only imagine that Soviet, er, Russian leader Putin enjoyed the first act of Trump's latest show.

And putting on a show was what it was all about. As it always is with this president. Here was Alexander Vershbow, a former NATO deputy secretary general, as quoted in The New York Times:

"I think it's the reality show that the president loves. There wasn't enough drama, so Trump has a tantrum, knocks over the table, and allies are used as props in his reality show."

Here's betting The Donald doesn't continue that act in his Monday confab with Putin. Because he'll be far too busy playing a different role: sycophant to the despot.